Pinch valve supplier Corflex Engineering has supplied pinch valves for a working pressure of 72 bar to a silver mine in Bolivia, South America.
The order, worth over R2-million, is for 12 pinch valves to operate on a tailings dam where pipeline pressure is supplied by positive displacement pumps. This is believed to be the highest pressure that a 200-mm pinch valve has ever been built for.
The high operating pressure required hydraulic operation of the valves. As there is no electrical power available on the tailings dam, each valve was fitted with its own hydraulic power pack and designed to be operated from a mobile generating set. The order was a new development for this size of high-pressure pinch valve, taking over seven months to produce.
The pinch valve sleeves were built by rubber product manufacturer Dunlop Industrial Products. These high-pressure sleeves and all other Corflex pinch valve sleeves are built to the highest standard required by Dunlop's strict quality assurance programme, ISO 9001:2008.
The 200-mm pinch valve sleeves have a design working pressure of 75 bar. The rubber hose sleeves have a test pressure of 150 bar, which is twice the highest recommended working pressure. To build these sleeves, Corflex had to design and build special tooling, as well as a test rig to test the sleeves.
To close and seal 200-mm pinch valves at 72 bar requires a minimum force of 44 t in addition to a good safety factor. To this end, a special valve body had to be designed and built. The valve body is fitted with two opposed nonrising hydraulic cylinders securely bolted to the body, with large-diameter high-tensile cap screws.
The two body halves are also securely bolted together using high-tensile bolts. The valves are very heavily built because of the high pressure. The finished product weighed over 1 600 kg. The valve bodies are designed to contain the sleeve test pressure in the event of a sleeve failure.
Open-frame pinch valves in high-pressure applications are potentially dangerous in the event of a sudden pinch valve sleeve failure, which is similar to a burst pipe. Corflex safety requirements only recommend that enclosed pinch valves are able to withstand the pinch valve sleeve test pressure, for all high-pressure applications.
Most pinch valves are built with rising actuators, which is generally the least expensive way of building pinch valves. However, for this order, the more expensive and stronger nonrising pincher actuation, where the pinchers move independently from both sides, must be used.
This order enabled Corflex, who supply pinch valves for both low- and high-pressure applications, to increase its size range for very high pressure pinch valves.
Corflex Engg is represented in India by Adroitt Flow Control Pvt. Ltd. Please contact us for more information on product & applications.
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